This invention relates generally to films suitable for "cook-in" packaging. More specifically, the invention relates to improved cook-in films which comprise a peelable laminate having an edible film peelably adhered to a protective film, and to methods of cooking a food product in such a peelable/cook-in laminate.
Food products are often processed, i.e., cooked, in a thermoplastic film package by, for example, immersing the package in hot water or placing the package in a steam-heated environment. This process is referred to as a "cook-in" process and the film used in the process is known as a "cook-in" film. Cook-in packaged foods are essentially foods cooked in a package. The processed and packaged food product may be refrigerated, shipped to a retailer, and stored until the processed food is to be consumed or, e.g., sliced and repackaged into smaller portions for customer display (e.g., sliced luncheon meat). Alternatively, the processed food may be immediately removed from the cook-in package and either consumed or sliced and repackaged for customer display.
Films for cook-in packaging must be structurally capable of withstanding exposure to cook-in time and temperature conditions while containing the food product. Cook-in time and temperature conditions typically involve a long, slow cook, for example, submersion in hot water at about 55.degree. C. to 65.degree. C. for about 1 to about 4 hours. Submersion in water or steam at 70.degree. C. to 100.degree. C. for up to 12 hours is also possible.
Following the cook-in process, the film package should substantially conform to the shape of the contained food product. This is preferably achieved by the film being heat-shrinkable under cook-in conditions to form a tightly-fitting package. In other words, the cook-in film desirably possesses sufficient shrink energy that submerging the packaged food product in hot water during the cook-in process will shrink the packaging film snugly around the contained product. Alternatively, the cook-in film package may be caused to shrink around the contained food product prior to initiating the cook-in procedure by e.g., placing the package in a heated environment prior to cooking.
The cook-in film should also possess sufficient product adherence to restrict or prevent "cook-out," i.e., collection of juices between the surface of the contained food product and the food-contact-surface of the packaging material during cook-in, thereby increasing product yield and providing a more aesthetically-appealing package.
It is often desirable to apply a modifier to the outer surface of the processed food product. For example, if the food product is poultry or ham, it may be desirable to impart smoke color, flavor, and odor to the outer surface of the cooked poultry or ham. This is often accomplished by applying "liquid smoke" to the outer surface of the food product during or after cooking. It would be desirable for the cook-in film to allow smoke color, flavor, and ordor to be transferred to the poultry or ham during the cook-in process.
Conventional cook-in films possess a number of undesirable drawbacks. Some films do not provide sufficient adherence to the surface of the food product to prevent cook-out. This results in reduced product yield and an unsightly package-appearance. Other cook-in films successfully prevent cook-out, but adhere to the surface of the food product with such adhesive strength that portions of the food product are torn away from the remainder of the food product when the cook-in film is peeled from the food product after cooking. That is, the cohesive force within the food product is overcome by the adhesive force between the cook-in film and the surface of the food product. As a result, product yield is reduced and the food product has an unsightly (pitted) surface-appearance.
A further drawback of many conventional cook-in films is their inability to serve as a vehicle for transferring a modifier to a food product during the cook-in process. Attempts to do so have been largely unsuccessful, often resulting in non-uniform or no transfer of the modifier. Consequentially, modifier must be applied to the food product after the cook-in process has been completed. This necessitates stripping the cook-in film from the cooked food product, applying the modifier to the surface of the food product, and then repackaging. Not only does this procedure add time, expense, and complexity to the cooking/packing process, but it increases the likelihood that the food product will become contaminated. That is, inasmuch as cooking sterilizes the food product, it is preferred that the food product not be removed from its cook-in package and handled until it is to be consumed or sliced for retail display.
Another material used for cook-in packaging is collagen. While this material is advantageous in certain respects, it is very expensive and provides no shrinkage during the cooking process. Hence, a tight, aesthically-pleasing package appearance is difficult to achieve with collagen and cook-out often occurs. In addition, collagen adheres very well to most food products, often resulting in product loss when the collagen is stripped away from the food product due to food particles product adhering to the collagen.
Accordingly, a need exists in the art for a cook-in packaging film which minimizes or prevents cook-out, can be peeled from the food product after cook-in without tearing away portions of the surface of the food product, and which facilitates the transfer of a modifier to the food product during the cook-in process.